From Parktown prawn to piece of art: a South African maker story

We recently covered a very special event called Art Machina, the art exhibit of local maker Rick Treweek featuring only 3D printed pieces.

One piece in the gallery was decisively more South African than the others. Lovingly titled Mr. Prawn by those involved in its creation, it’s a sculpture of a Parktown Prawn that began life as a real bug and evolved into an impressive 3D printed sculpture.

The story of that journey is worth telling, so let’s get into it.

For our international readers, the Parktown Prawn, or Libanasidus vittatus, is a type of cricket found in SA. It’s named after the suburb of Parktown in Johannesburg, the country’s largest city.

It’s an animal the rest of the world has not had to deal with and, let us tell you, that’s a good thing. While not dangerous, it’s worryingly large and, if some sources are to be believed, can grow to seven centimetres in length.

Viewers of the classic Sci-fi flick District 9 are already unknowingly familiar with this bug, as the aliens are referred to as “prawns”. This wasn’t a slur against prawns, those tasty shellfish comparable to shrimp in the rest of the word, but rather towards Parktown Prawns.

You can see the similarities in the aliens’ design as well as their love for cat food, as real Parktown Prawns to have propensity for eating food intended for pets.

(Left) a real prawn and (right) a movie prawn. Leave it to movies to set unrealistic beauty standards…

Nomenclature lesson over, Mr Prawn’s story started as a Facebook post. Treweek used his account to put out an odd request that read like a wanted poster: “One Parktown Prawn, dead or alive”.

After a few false leads, he was contacted by Donald McCallum, a member of the University of the Witwatersrand’s entomology department. McCallum provided Treweek with the dead insect he needed.

With a dead prawn acquired, Treweek needed a way to scan it and create a model to 3D print. To that end, he tapped up Jaco Moolman, an expert in the field of 3D scanning.

Moolman’s background is fascinating; we’ll hopefully have a full feature about him soon, but trust us when we say that he knows his stuff.

Moolman’s quest to create a truly high quality scan of a bug started with a dung beetle and not the prawn. He posted about this on Facebook and, a few months later when Treweek needed help, he contacted Moolman.

Moolman’s first attempt to scan the prawn involved a white light scanner, which would project a pattern on the insect which he could then capture. While potentially a good idea, it would have taken far too much time using Moolman’s old, home-built 3D scanner. Attempt number two involved laser scanning which worked, but didn’t provide enough detail.

In the end, Moolman’s solution was to capture thousands of images of the prawn that could be stitched together into a 3D model. This process started off with a 24 MP Sony DSLR camera.

“It seems my ‘macro’ lens I have for this camera was not “macro-y” enough and I lost a lot of image space using this camera,'” said Moolman. “When using photos to create 3D models every pixel counts.”

He then settled on a non-DSLR Coolpix Nikon camera as the lens setup worked perfectly. The process of capturing thousands of pictures raised a few problems, however – light reflections produced models that looked grainy. This was solved by adding a powder to the surface of the prawn.

Despite careful planning and reference markers (those red marks in the image above), another huge challenge was flipping the prawn over for some sots of the underbelly.

About three weeks later Moolman had two high resolution models – one of the top, and one of the bottom. the final leg of the journey was actually the easiest part:

“I was hoping the application would recognise that it was the same prawn, however, due to less than perfect lighting it was unable to. I used Zbrush and Meshlab to scale and align the models. I then projected the detail from the top model onto the bottom one to then have all the detail on one model. I actually did not spend much time in cleaning up the model. You know, fixing holes, smoothing surfaces, defining edges. The final model I sent to Mr. Rick was pretty much raw scan data. From there it was over to Mr. Rick to create his artwork.”

Treweek (or Mr. Rick) then did his thing, adding a host of other creations to the back of the prawn which gives it a rather creepy appearance.

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